Method for fabricating semiconductor device

ABSTRACT

A method for fabricating a semiconductor device comprising: providing a semiconductor substrate on which a transistor made of a gate electrode, a source/drain is formed; forming a first insulating layer on the semiconductor substrate, with bit-line contact holes and a storage node contact hole being formed in the insulating layer to expose the source and drain; forming bit-line contact plugs and storage node in the bit-line contact holes and the storage node contact hole; removing the first insulating layer; forming a second insulating layer on the resultant structure; forming a first conductive layer on the second insulating layer; forming a third insulating layer; forming bit-line contact holes by selective removal of the first conductive layer and the third insulating layer opposing the upper surface of the bit-line contact plug; and forming a second conductive layer in the bit-line contact holes.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method for fabricating a semiconductor device, and more particularly to a method for fabricating a semiconductor device, which can simplify the fabrication process of a capacitor and reduce the production costs.

[0003] 2. Description of the Prior Art

[0004] As generally known in the art, in a conventional process of fabricating a capacitor in a semiconductor device, at the time of contact hole formation so as to form a second contact plug for a bit-line, difficulty of forming contact holes production arises because etch selection rate for each layer have varied, thus resulting the increase of costs.

[0005] Further, at the time of forming a lower electrode, it has been troublesome to use two separate masks, one for a storage node contact and the other for a storage node.

[0006] Accordingly, as regards the conventional process of fabricating a capacitor in a semiconductor device, unnecessary separate masking processes are required, such as one masking process for the storage node contact and a separate masking process for the storage node, so that fabrication process has been complicated and production costs have increased.

SUMMARY OF THE INVENTION

[0007] Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a method for fabricating a semiconductor device, which can simplify the fabrication process of a capacitor in a semiconductor device and reduce the production costs thereof.

[0008] In order to accomplish this object, there is provided a method for fabricating a semiconductor device, comprising the steps of: providing a semiconductor substrate on which a transistor made of a gate electrode, and a source/drain is formed; forming a first insulating layer on the semiconductor substrate, bit-line contact holes and a storage node contact hole being formed in the insulating layer to expose the source/drain; forming a bit-line contact plug and storage node in the bit-line contact holes and the storage node contact hole; removing the remaining first insulating layer between the bit-line contact plug and the storage node; after removing the first insulating layer, forming a second insulating layer on the resultant structure including the bit-line contact plug and the storage node; forming a first conductive layer on the second insulating layer; forming a third insulating layer on the first conductive layer; forming bit-line contact holes by selective removal of the first conductive layer and the third insulating layer which is opposite to the upper surface of the bit-line contact plug; and forming a second conductive layer in the bit-line contact holes.

[0009] In this embodiment of the present invention, the first conductive layer embodies a plate electrode, and the second conductive layer embodies a bit-line.

[0010] Also, the step of forming the bit-line contact plug and the storage node is carried out using at least one layer selected from a group composed of an anisotropic epitaxial silicon layer, an anisotropic polysilicon layer, an anisotropic selective tungsten layer, an isotropic epitaxial silicon layer, and an isotropic polysilicon layer.

[0011] Additionally, a step of forming the bit-line contact plug and the storage node with an anisotropic polysilicon layer comprises: forming an anisotropic polysilicon layer on the first insulating layer, thus filling the bit-line contact holes and the storage node contact hole having been made in the first insulating layer, and forming a bit-line contact plug and a storage node by performing a CMP process of the anisotropic polysilicon layer.

[0012] Also, the etch selection rate between the second insulating layer, the first conductive layer and a capacitor insulating layer is about 1:1:1.

[0013] Further, the method for fabricating a semiconductor device of the present invention comprises forming a spacer-insulating layer at the side walls of the bit-line contact holes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0015] FIGS. 1 to 3 are cross-sectional views for illustrating each step of a method for fabricating a semiconductor device in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following description and drawings, the same reference numerals are used to designate the same or similar components, and so repetition of the description of the same or similar components will be omitted.

[0017] FIGS. 1 to 3 are cross-sectional views for illustrating each step of a method for fabricating a semiconductor device in accordance with the present invention.

[0018] Referring to FIG. 1, in accordance with a preferred embodiment of the present invention, a field oxide layer 23 defining an active region and an inactive region is first formed in a semiconductor substrate 21, and sequentially a gate insulating layer 25, a gate electrode 27 and a mask insulating layer 29 are formed in the active region of the semiconductor substrate 21.

[0019] Then, impurities having a low concentration are implanted into the semiconductor substrate 21 below both sides of the mask insulating layer 29 to form an N-LDD region 31, thereby producing a nitride layer spacer 33 at the side of the gate electrode 27.

[0020] Next, a contact plug 35 for a bit-line and a storage node contact plug 37 are formed on the N type LDD region 33 by using either an anisotropic epitaxial silicon layer or an anisotropic polysilicon layer, or both an isotropic epitaxial silicon layer and an isotropic polysilicon layer.

[0021] Referring to FIG. 2, a first insulating layer 38 is deposited on the resultant structure, and a thermi-insulating layer (not shown) is thickly deposited on the first insulating layer 38, then performing CMP process to polish back the resultant structure, thus exposing the bit-line contact plug 35 and the storage node contact plug 37.

[0022] Then, as desired, an anisotropic epitaxial layer, anisotropic selective tungsten layer or an anisotropic polysilicon layer are grown in the second bit-line contact plug (not shown) and the storage node contact plug contact hole (not shown) by using the first bit-line contact plug 35 and the storage node contact plug 37 as seeds, thereby forming a second bit-line contact plug 39 a and a pillar type storage node 39 b.

[0023] Next, the remaining thermi-insulating layer (not shown) is removed, and a capacitor insulating layer 41 is formed on the surface of the entire resultant structure including the second bit-line contact plug 39 a and the pillar type storage node 39 b, and then a plate electrode 43 is formed on the capacitor insulating layer 41.

[0024] Subsequently, a second insulating layer 45 is deposited thickly on the plate electrode 43 to result in planarization of the resultant structure, and a photoresist film pattern 47, which exposes the second insulating layer 45 opposing the second bit-line contact plug 39 a, is formed on the second insulating layer 45.

[0025] Then, bit-line contact holes 49 are formed by selective removal of the exposed second insulating layer 45, using the photoresist film pattern 47 as an etch-mask.

[0026] Referring now to FIG. 3, spacer-insulating layers 51 are formed at the side walls of the bit-line contact holes 49 after the removal of the photoresist film pattern 45, and a conductive layer 53 for formation of the bit-line, electrically connected with the second bit-line contact plug 39 a, is formed on the second insulating layer 45 including the bit-line contact hole 49 having been formed between the spacer-insulating layers 51.

[0027] Then, although not shown in the drawing, a bit-line (not shown) is formed through selective patterning of the conductive layer 53 using a bit-line mask (not shown).

[0028] Alternatively, according to another embodiment of the present invention, an insulating layer (not shown) is deposited on the entire resultant structure including the first bit-line contact plug 35 and the storage node contact plug 37, and then a photoresist film pattern (not shown) is formed on the insulating layer to expose the first bit-line contact plug 35 and the storage node contact plug 37 without forming a thermi-insulating layer (not shown) in the process of forming the second bit-line contact plug 39 a and the pillar type storage node 39 b.

[0029] Next, a contact hole for formation of a second bit-line contact plug and a contact hole for formation of a storage node are formed through patterning of the insulating layer (not shown) by using the photoresist film pattern (not shown) as an etch-mask.

[0030] Subsequently, a polysilicon layer is deposited on the resultant structure including the contact hole for formation of a second bit-line contact plug and the contact hole for formation of a storage node to fill the contact hole for formation of a second bit-line contact plug and the contact hole for formation of a storage node, and performing a CMP process to result in the formation of the second bit-line contact plug and the storage node.

[0031] Then, the subsequent processes, as are performed in the first embodiment of the present invention, are performed.

[0032] The following advantages are achieved according to the method for fabricating a semiconductor device of the present invention.

[0033] In the present invention, production costs are reduced because contact holes can be formed at one time through forming the contact hole for the second bit-line contact plug with an etch selection rate between the second insulating layer, the plating electrode and the capacitor insulating layer being a rate of 1:1:1. Further, separate masks, one for forming the storage node and another for the storage node contact, are not required.

[0034] Accordingly, the present invention can abbreviate unnecessary separate masking processes, such as a separate masking process for the storage node contact and a separate masking process for the storage node, thereby simplifying the fabricating process and reducing the production costs.

[0035] Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 

What is claimed is:
 1. A method for fabricating a semiconductor device, comprising the steps of: providing a semiconductor substrate on which a transistor made of a gate electrode, a source/drain is formed; forming a first insulating layer on the semiconductor substrate, bit-line contact holes and a storage node contact hole being formed in the insulating layer to expose the source and drain; forming bit-line contact plugs and storage node in the bit-line contact holes and the storage node contact hole; removing the first insulating layer remaining between the bit-line contact plug and the storage node; after removing the first insulating layer, forming a second insulating layer on the resultant structure including the bit-line contact plug and the storage node; forming a first conductive layer on the second insulating layer; forming a third insulating layer on the first conductive layer; forming bit-line contact holes by selective removal of the first conductive layer and the third insulating layer opposing to the upper surface of the bit-line contact plug; and forming a second conductive layer in the bit-line contact holes.
 2. The method for fabricating a semiconductor device according to claim 1, wherein the first conductive layer constitutes a plate electrode and the second conductive layer constitutes a bit-line.
 3. The method for fabricating a semiconductor device according to claim 1, wherein the step of forming the bit-line contact plug and the storage node is carried out using any one layer selected from a group composed of an anisotropic epitaxial silicon layer, an anisotropic polysilicon layer, an anisotropic selective tungsten layer, an isotropic epitaxial silicon layer, and an isotropic polysilicon layer.
 4. The method for fabricating a semiconductor device according to claim 3, wherein a step of forming the bit-line contact plug and the storage node with an anisotropic polysilicon layer comprises: forming an anisotropic polysilicon layer on the first insulating layer, thus filling the bit-line contact holes and the storage node contact hole having been made in the first insulating layer; and forming bit-line contact plugs and a storage node by performing a CMP process on the anisotropic polysilicon layer.
 5. The method for fabricating a semiconductor device according to claim 1, wherein an etch selection rate between the second insulating layer, the first conductive layer and a capacitor insulating layer is about 1:1:1.
 6. The method for fabricating a semiconductor device according to claim 1, further comprising step of forming a spacer-insulating layer at the side walls of the bit-line contact holes. 